[0001] The invention is related to an elastic torsion element for connecting a rotor blade
to a rotor hub of a rotor. The invention is further related to a rotary wing aircraft
with a rotor that comprises such an elastic torsion element.
[0002] In bearingless or hinge- and bearingless rotor systems, elastic torsion elements
are used to connect rotor blades of a multi-blade rotor of a rotary wing aircraft
to an associated rotor hub or shaft of the aircraft. During operation, i. e. rotation
of the multi-blade rotor, a respective elastic torsion element must withstand tremendous
centrifugal forces that the rotor blades apply thereto, while permitting their flapping,
pitch and lead-lag motions.
[0003] Such an elastic torsion element is usually implemented by means of a so-called "flexbeam"
element. In general, a flexbeam element is a special, in particular fiber reinforced
composite material element that is flexible enough in bending without discrete hinges,
in the case of a hingeless rotor system, or in bending and in torsion to allow twisting
for blade movement without bearings, in the case of a bearingless rotor system.
[0004] A flexbeam element usually realizes a flapwise-soft region that enables flapping
of the associated rotor blade in the vertical direction, i. e. rotation of the associated
rotor blade out of the respective rotation plane defined by the given multi-blade
rotor. Thus, the flapwise-soft region constitutes a fictitious horizontally oriented
axis, a so-called virtual flapping hinge, about which the associated rotor blade flaps,
i. e. executes upward and downward flapwise motions in a bearingless or a hinge- and
bearingless rotor system. Furthermore, only in a bearingless rotor system, the flexbeam
element usually comprises a torsion weak region that enables torsion, i. e. rotation
of the associated rotor blade around its respective rotor blade axis. Moreover, the
flexbeam element usually possesses a lead-lag-soft region that permits motions of
an associated rotor blade in a bearingless or a hinge- and bearingless rotor system
in the lead-lag direction. The lead-lag-soft region thus constitutes a fictitious
vertically oriented axis, a so-called virtual lead-lag hinge, about which the rotor
blade executes forward and backward lead-lag motions, i. e. rotation of the associated
rotor blade within a respective rotation plane defined by a given multi-blade rotor.
Usually, the lead-lag-soft region and the torsion weak region are arranged between
the flapwise-soft region and a respective rotor blade attachment, where the associated
rotor blade is attached, or a transition zone into an aerodynamic profile that forms
the associated rotor blade.
[0005] Generally, it is advantageous to realize the lead-lag-soft region and a torsion weak
region such that the lead-lag-soft region is integrated into the torsion weak region
which is, preferably, resistant against excessive deformation and buckling deformation
under flapping loads without additional supports, such as e. g. a specific flap stop.
Consequently, such a torsion weak region with integrated lead-lag-soft region leads
to transition from a shape with high lead-lag stiffness and low flapping stiffness
into a shape with low lead-lag stiffness and high flapping stiffness, due to its arrangement
between the flapwise-soft region and the respective rotor blade attachment. However,
respective flexbeam elements are usually rather complex and consist of composite components
that are very elaborate and difficult to manufacture. Thus, these composite components
are generally expensive.
[0006] The document
EP 1 431 176 A1 describes a flexbeam element with flapping portions and lead-lag and feathering portions.
Each lead-lag and feathering portion has a central portion with an elongated and narrow
width; middle portions each of which continuously connects to the central portion
and branches from both ends of the central portion extending along the longitudinal
direction thereof, and extends upward and downward; and edge portions each of which
continuously connects to a respective middle portion and bends from each end of the
respective middle portion and extends almost in parallel with the central portion.
More specifically, each lead-lag and feathering portion has an at least approximately
X-shaped cross-section. However, such a cross-section is complicated and elaborate
to manufacture and, consequently, expensive, and provides for a comparatively high
lead-lag stiffness.
[0007] One possibility of simplifying the above-described design of the flexbeam according
to
EP 1 431 176 A1 would be by simply stacking large layers on top of each other without bending corresponding
fiber directions within the planes of respectively used fiber plies. Furthermore,
corresponding fibers of respectively applied composite materials should at least essentially
extend uninterruptedly between both axial ends of the flexbeam in order to achieve
high strengths, especially high fatigue strengths.
[0008] The documents
US 2015/0158582 A1,
US 8,821,128 B1, and
CA 2 650 760 A1 describe flexbeams with designs that can be manufactured more easily and, thus, cheaper
as well as with comparatively few interrupted fibers. However, these flexbeams provide
for a comparatively low flapping stiffness and a comparatively high lead-lag stiffness
in a respective torsion weak region having an integrated lead-lag-soft region. Thus,
additional structures, such as e. g. flap stops, are required in order to prevent
excessive deformation. Furthermore, comparatively long lead-lag-soft regions are required,
resulting in higher weight and lower aerodynamic performance of the flexbeams.
[0009] If, however, respective fiber layers of the flexbeams according to the documents
US 2015/0158582 A1,
US 8,821,128 B1, and
CA 2 650 760 A1 are stacked high enough in order to achieve a required, sufficiently high flapping
stiffness, then corresponding shear centers of the flexbeams which are separated by
slots would be comparatively distant from a respective pitching resp. torsion axis
of the flexbeam. Such a large distance of the shear centers from the pitching resp.
tortion axis nevertheless leads to a high torsional stiffness, especially when a centrifugal
load is applied to the flexbeam. The documents
EP2832640,
US2010278648 and
US5263821 disclose elastic torsion elements.
[0010] It is, therefore, an object of the present invention to provide a new elastic torsion
element for connecting a rotor blade to a rotor hub of a rotor. This new elastic torsion
element should comprise an integrated elastic lead-lag hinge and should be manufacturable
easily and at comparatively low cost.
[0011] This object is solved by an elastic torsion element for connecting a rotor blade
to a rotor hub of a rotor, the elastic torsion element comprising the features of
claim 1.
[0012] More specifically, according to the present invention an elastic torsion element
for connecting a rotor blade to a rotor hub of a rotor comprises at least two elastically
deformable plates. Each one of the at least two elastically deformable plates comprises
fiber reinforced polymers. Respective fibers of the fiber reinforced polymers of each
one of the at least two elastically deformable plates are at least arranged along
one of a first and a second dominant fiber directions, wherein the first dominant
fiber direction crosses the second dominant fiber direction in a predetermined fiber
direction crossing region. The elastic torsion element comprises an integrated elastic
lead-lag hinge that is formed at the predetermined fiber direction crossing region.
[0013] The at least two elastically deformable plates are manufactured as composite plates
using glass, basalt, carbon and/or aramid fiber fabrics and rovings that are oriented
in different angles with respect to each other. More specifically, in order to enable
transfer of comparatively high centrifugal forces and lead-lag as well as flapping
bending moments, preferably most of the respective fibers are oriented within +/-15°
with respect to a virtual line that is oriented in parallel to a respective pitching
resp. torsion axis of the rotor blade.
[0014] More specifically, preferably comparatively large roving plies are oriented in different
directions between the +/-15° and cross each other in the predetermined fiber direction
crossing region. This leads to a comparatively narrow section of the elastic torsion
element at said predetermined fiber direction crossing region, where the large roving
plies preferably overlap. This comparatively narrow predetermined fiber direction
crossing region has a comparatively low lead-lag bending stiffness according to one
aspect and, thereby, defines the integrated elastic lead-lag hinge.
[0015] According to one aspect, the elastic torsion element further defines an elastic flapping
hinge area and the at least two elastically deformable plates become wider and thinner
towards the elastic flapping hinge area, which is advantageous for a respective transition
into a selected shape of the elastic flapping hinge area. The elastic flapping hinge
area preferably exhibits a comparatively high lead-lag stiffness and a comparatively
low flapping stiffness.
[0016] Advantageously, the at least two elastically deformable plates also become wider
and thinner towards an associated rotor blade attachment area, where the elastic torsion
element is connected to the rotor blade. Alternatively, the rotor blade attachment
area can be implemented by an integrated transition area that transitions into an
underlying aerodynamic profile that forms the rotor blade.
[0017] According to one aspect, the elastic torsion element and, more specifically, the
at least two elastically deformable plates exhibit curved, e. g. U-shaped cross-sections.
A respective shear center of such U-shaped cross sections is preferably close to the
pitching resp. torsion axis of the rotor blade, respectively of the elastic torsion
element. However, an elastically deformable plate that is directly arranged at the
pitching resp. torsion axis of the rotor blade preferably merely exhibits a point
symmetric cross-sectional shape, e. g. a rectangular shape or an S-shape.
[0018] Advantageously, the U-shaped cross-sections can be created by smooth transitions
from flat shapes, e. g. shapes that are provided in the elastic flapping hinge area
and/or a respective rotor blade attachment area or transition area to the aerodynamic
profile, with minimal bending of respective fibers within an underlying plane of the
plies. Furthermore, by separating the cross-sections, i. e. each elastically deformable
plate, into multiple separate plates, a corresponding torsion resistance of the elastic
torsion element can be reduced further. Moreover, both the location of the shear centers
and the separation into multiple elastically deformable plates reduce a corresponding
Saint Vernant component of torsion stiffness. Preferably, the multiple elastically
deformable plates form an overall cross-sectional shape that is similar to a star-shape,
which is advantageous for low warping stiffness (a so-called "Wölbsteifigkeit"). Advantageously,
the curved U-shaped cross-sections exhibit comparatively high resistance against buckling.
[0019] According to one aspect, the integrated elastic lead-lag hinge is arranged in an
area of the inventive elastic torsion element that is clearly separated from other
areas of the elastic torsion element, such as a respective elastic flapping hinge
area, a rotor blade attachment area, or a respective transition area to an associated
aerodynamic profile. Preferably, the integrated elastic lead-lag hinge exhibits a
low lead-lag stiffness and a high flapping stiffness, i. e. at least a lead-lag stiffness
that is smaller than the associated flapping stiffness. Also, preferably, the inventive
elastic torsion element exhibits a comparatively low torsion stiffness and a comparatively
high resistance against buckling under flapping loads. Moreover, overlapping areas
of a respective torsion weak region and the integrated elastic lead-lag hinge are
preferably provided.
[0020] In a preferred realization of the inventive elastic torsion element, only comparatively
few interrupted fibers are required and only comparatively few splicings are necessary.
Advantageously, each one of the elastically deformable plates can be manufactured
by stacking separate plies vertically, with little or no bending of respective composite
fibers within the plane of the plies.
[0021] According to one aspect, the inventive elastic torsion element comprises four separate
elastically deformable plates that form the integrated elastic lead-lag hinge. Each
one of these four elastically deformable plates is preferably implemented with two
dominant fiber directions for respective fibers that are provided to transfer at least
most of centrifugal forces as well as flapping and lead-lag bending forces that are
applied to the elastic torsion element in operation. The two dominant fiber directions
preferably cross each other in the predetermined fiber direction crossing region,
such that the inventive elastic torsion element is narrowest in the location where
the two dominant fiber directions cross each other, and, therefore, overlap. On axial
ends of the inventive elastic torsion element towards a respective flapping hinge
area, and towards a respective rotor blade attachment area or transition zone to an
associated aerodynamic profile, the two dominant fiber directions preferably diverge
in order to form areas with only one dominant fiber direction.
[0022] Preferably, in order to avoid sharp corners and stepwise transitions, the elastic
torsion element is smoothed in selected areas by adding material with interrupted
fibers. Furthermore, composite layers with differing orientations and composite fabric
layers are added in order to increase a respective in-plane shear stiffness of the
inventive elastic torsion element. Moreover, by adding such additional layers, also
a bearing laminate can be created that is suitable for application of e. g. bolts
and/or rivets, and furthermore excessively thin sections can be avoided and reinforced
against buckling.
[0023] According to one aspect, the four elastically deformable plates are formed such that
they transition from comparatively flat shapes that are embodied adjacent to a respective
flapping hinge area of the elastic torsion element into U-shaped cross-sections in
an effective area of the integrated elastic lead-lag hinge. Respective shear centers
of these cross-sections are preferably close to an underlying pitching resp. torsion
axis of the inventive elastic torsion element.
[0024] Advantageously, the inventive elastic torsion element has a comparatively easy design
so that it can be manufactured easily and in a cost-effective manner. More specifically,
it can preferably be embodied by using simple components, i. e. the elastically deformable
plates, which are preferentially plate-, strip-, bar- and/or lath-shaped elastic members
with simple rectangular cross-sections that may preferably even allow for connection
to associated rotor blades with no need for a cross-section change. Such plate-, strip-,
bar- and/or lath-shaped elastic members may have a comparatively short length.
[0025] Preferably, the plate-, strip-, bar- and/or lath-shaped elastic members are manufactured
using fiber composite materials. Preferably, fiber reinforced polymers are used, such
as carbon fiber reinforced polymers, glass fiber reinforced polymers, aramid fiber
reinforced polymers or basalt fiber reinforced polymers. More specifically, the inventive
elastic torsion element and, in particular, its integrated elastic lead-lag hinge
preferably comprises two or more elastically deformable plates that are stacked on
top of each other. Each one of the at least two elastically deformable plates preferably
comprises fiber reinforced polymers.
[0026] According to a preferred embodiment, the fiber reinforced polymers comprise carbon,
glass, aramid and/or basalt fiber fabrics and rovings.
[0027] According to a further preferred embodiment, the respective fibers of the fiber reinforced
polymers of each one of the at least two elastically deformable plates are at least
essentially oriented within +/-15° with respect to a longitudinal axis of the elastic
torsion element.
[0028] According to a further preferred embodiment, the respective fibers of the fiber reinforced
polymers of each one of the at least two elastically deformable plates are at least
arranged along one third dominant fiber direction that crosses at least one of the
first dominant fiber direction and the second dominant fiber direction.
[0029] According to a further preferred embodiment, the at least two elastically deformable
plates comprise at least a first and a second elastically deformable plate that exhibit
at least approximately an arc-shaped cross-section in a respective elastic lead-lag
hinge area of the integrated elastic lead-lag hinge.
[0030] According to a further preferred embodiment, the at least two elastically deformable
plates comprise at least one third elastically deformable plate that is arranged between
the first and second elastically deformable plates and exhibits a point symmetric
cross-section in the respective elastic lead-lag hinge area.
[0031] According to a further preferred embodiment, the at least one third elastically deformable
plate exhibits a rectangular cross-section in the respective elastic lead-lag hinge
area.
[0032] According to a further preferred embodiment, the at least one third elastically deformable
plate exhibits at least approximately an S-shaped cross-section in the respective
elastic lead-lag hinge area.
[0033] According to a further preferred embodiment, the at least approximately arc-shaped
cross-section in the respective elastic lead-lag hinge area of the integrated elastic
lead-lag hinge transitions along a longitudinal axis of the elastic torsion element
towards an elastic flapping hinge area into a flat cross-section.
[0034] According to a further preferred embodiment, the at least approximately arc-shaped
cross-section in the respective elastic lead-lag hinge area of the integrated elastic
lead-lag hinge transitions along a longitudinal axis of the elastic torsion element
towards a rotor blade attachment area or transition zone into a flat cross-section.
[0035] According to a further preferred embodiment, the integrated elastic lead-lag hinge
is formed by a narrowest cross-section area of the elastic torsion element.
[0036] According to a further preferred embodiment, the at least two elastically deformable
plates comprise at least two upper elastically deformable plates and at least two
lower elastically deformable plates, wherein the at least two lower elastically deformable
plates are arranged in reflection symmetry to the at least two lower elastically deformable
plates.
[0037] According to a further preferred embodiment, the at least two lower elastically deformable
plates are attached to the at least two lower elastically deformable plates by means
of a bolted connection, the bolted connection being provided at least approximately
at a longitudinal axis of the elastic torsion element.
[0038] According to a further preferred embodiment, at least one first and one second elastically
deformable plates of the at least two elastically deformable plates are integrated
into a single slotted elastically deformable plate, wherein the at least one first
and one second elastically deformable plates are at least partly separated in the
single slotted elastically deformable plate by means of an associated separating slot.
[0039] The present invention further provides a rotary wing aircraft with at least one rotor
that comprises at least two rotor blades, and with a rotor hub, each one of the at
least two rotor blades being connected to the rotor hub via an elastic torsion element
that is embodied as described above.
[0040] Preferred embodiments of the invention are outlined by way of example in the following
description with reference to the attached drawings. In these attached drawings, identical
or identically functioning components and elements are labeled with identical reference
numbers and characters and are, consequently, only described once in the following
description.
- Figure 1 shows a partially perspective top view of a multi-blade rotor having at least
one elastic torsion element according to the invention,
- Figure 2 shows a top view of a partial laminate of a selected one of the elastic torsion
elements of Figure 1, comprising only uninterrupted fibers following dominant fiber
directions,
- Figure 3 shows a top view of a full laminate of the elastic torsion element of Figure
2 with the uninterrupted fibers, as well as with interrupted fibers and spliced plies,
- Figure 4 shows a cut view of the full laminate of Figure 3, seen along a cut line
IV-IV in Figure 3,
- Figure 5 shows a cut view of the full laminate of Figure 3, seen along a cut line
V-V in Figure 3,
- Figure 6 shows a top view of a partial laminate of an alternative elastic torsion
element having uninterrupted fibers following dominant fiber directions,
- Figure 7 shows a top view of a full laminate of the elastic torsion element of Figure
6 with the uninterrupted fibers, as well as with interrupted fibers and spliced plies,
- Figure 8 shows a cut view of the full laminate of Figure 6, seen along a cut line
VIII-VIII of Figure 7,
- Figure 9 shows the cut view of Figure 8 according to a first variant,
- Figure 10 shows the cut view of Figure 8 according to a second variant, and
- Figure 11 shows a partially perspective top view of a selected one of the elastic
torsion elements of Figure 1, according to still another variant of the present invention.
[0041] Figure 1 shows a multi-blade rotor 1 of a rotary wing aircraft, in particular a multi-blade
rotor for a main rotor of a helicopter. The multi-blade rotor 1 illustratively comprises
a rotor shaft 8 that is embodied with a rotor hub 7. Furthermore, a rotor head covering
cap 9 is provided for covering a central portion of the multi-blade rotor 1, which
comprises the rotor hub 7 and which illustratively defines an associated rotor head.
The rotor head covering cap 9 is shown with an illustrative cut-out 9a, where the
rotor head covering cap 9 is partially cut away in order to permit amongst others
the illustration of the rotor hub 7.
[0042] The multi-blade rotor 1 is preferably embodied as a bearingless rotor having a multiplicity
of elastic hinge units 3 as interfaces between the rotor shaft 8, i. e. the rotor
hub 7, and a plurality of rotor blades 2a, 2b, 2c, 2d, 2e. It should, however, be
noted that these rotor blades 2a, 2b, 2c, 2d, 2e are not shown in greater detail,
neither in Figure 1 nor in the remaining figures, for simplicity and clarity of the
drawings. Furthermore, it should be noted that the expression "multi-blade rotor"
should be construed in the context of the present invention such that it encompasses
all rotors having at least two rotor blades.
[0043] The multiplicity of elastic hinge units 3 preferably implements a multiplicity of
elastic torsion elements 5, i. e. elastic torsion elements 5a, 5b, 5c, 5d, 5e. It
should, however, be noted that for simplicity and clarity of the drawings only a single
elastic hinge unit of the multiplicity of elastic hinge units is designated with the
reference number 3 and described representatively hereinafter for all elastic hinge
units of the multiplicity of elastic hinge units, which are preferably at least similarly
embodied.
[0044] More specifically, the multiplicity of elastic hinge units defines a predetermined
number of elastic torsion elements 5a, 5b, 5c, 5d, 5e of the multi-blade rotor 1,
such that each one of the elastic torsion elements 5a, 5b, 5c, 5d, 5e is associated
with a given rotor blade of the plurality of rotor blades 2a, 2b, 2c, 2d, 2e. Furthermore,
the elastic torsion elements 5a, 5b, 5c, 5d, 5e preferably comprise a plurality of
hub connecting points 10 for connection to the rotor hub 7. For simplicity and clarity
of the drawings, however, only a single hub connecting point of the elastic torsion
element 5d is designated with the reference sign 10a. Moreover, each one of the elastic
torsion elements 5a, 5b, 5c, 5d, 5e preferably comprises one or more blade connecting
points 3a, 3b, 3c, 3d, 3e for connection to an associated one of the rotor blades
2a, 2b, 2c, 2d, 2e. Illustratively, the rotor blades 2a, 2b, 2c, 2d, 2e are connected
to the elastic torsion elements 5a, 5b, 5c, 5d, 5e at the blade connecting points
3a, 3b, 3c, 3d, 3e and can be disconnected therefrom, if required.
[0045] However, according to one aspect the rotor blades 2a, 2b, 2c, 2d, 2e and the elastic
torsion elements 5a, 5b, 5c, 5d, 5e, i. e. the multiplicity of elastic hinge units
3, can also be implemented as integral components, so that they could not be disconnected
from each other. In this case, the blade connecting points 3a, 3b, 3c, 3d, 3e merely
define virtual transition points resp. transition zones to associated aerodynamic
profiles that form the rotor blades 2a, 2b, 2c, 2d, 2e.
[0046] Each one of the elastic torsion elements 5a, 5b, 5c, 5d, 5e is preferably further
associated with a control cuff of a multiplicity of control cuffs 6, i. e. control
cuffs 6a, 6b, 6c, 6d, 6e. These control cuffs 6a, 6b, 6c, 6d, 6e are preferably adapted
for setting in operation of the multi-blade rotor 1 a current pitch or blade angle
of the rotor blades 2a, 2b, 2c, 2d, 2e by controlling a current torsion of the elastic
torsion elements 5a, 5b, 5c, 5d, 5e, i. e. of the multiplicity of elastic hinge units.
For instance, the control cuff 6d is driveable for setting the current pitch or blade
angle of the rotor blade 2d by controlling the current torsion of the elastic torsion
element 5d, i. e. the current torsion of the elastic hinge unit 3.
[0047] According to one aspect, the elastic torsion element 5d comprises at least an integrated
elastic lead-lag hinge 4 that is illustratively provided for enabling lead-lag motions
of the rotor blade 2d relative to the rotor hub 7. Optionally, the elastic torsion
element 5d may further comprise an elastic flapping hinge area (13b in Figure 2).
Illustratively, the elastic torsion element 5d defines a longitudinal direction 5f
directed, by way of example, from the rotor shaft 8 to its blade connecting point
3d.
[0048] Figure 2 shows the elastic torsion element 5d with the integrated elastic lead-lag
hinge 4 of Figure 1. The elastic torsion element 5d has the longitudinal axis 5f of
Figure 1 and is representatively illustrated for all elastic torsion elements of Figure
1. In other words, all elastic torsion elements 5a, 5b, 5c, 5d, 5e of the multi-blade
rotor 1 of Figure 1 are preferably identically formed, at least within usual predetermined
manufacturing tolerances.
[0049] According to one aspect, the elastic torsion element 5d comprises a multiplicity
of elastically deformable plates 11. More specifically, the elastic torsion element
5d preferably comprises at least two elastically deformable plates 11a (and 11b in
Figure 4 and Figure 5). Illustratively, and due to a selected viewing direction in
Figure 2, however, only the elastically deformable plate 11a of the multiplicity of
elastically deformable plates 11 is shown.
[0050] By way of example, the elastic torsion element 5d is only shown as partial laminate
20, which illustratively only comprises uninterrupted fibers following predetermined
dominant fiber directions. More specifically, the elastically deformable plate 11a
preferably comprises fiber reinforced polymers. For instance, the fiber reinforced
polymers comprise carbon, glass, aramid and/or basalt fiber fabrics and rovings. According
to one aspect, respective fibers of the fiber reinforced polymers of the elastically
deformable plate 11a are preferably uninterrupted and selectively arranged along one
of at least two dominant fiber directions 12a, 12b. However, while Figure 2 only shows
a first and a second dominant fiber direction 12a, 12b, provision of more than these
two dominant fiber directions 12a, 12b is likewise contemplated, as illustrated by
way of example in Figure 6. Preferably, the respective fibers of the fiber reinforced
polymers of the elastically deformable plate 11a are at least essentially oriented
with +/-15° with respect to the longitudinal axis 5f of the elastic torsion element
5d.
[0051] According to one aspect, the first dominant fiber direction 12a crosses the second
dominant fiber direction 12b in a predetermined fiber direction crossing region 14.
At the predetermined fiber direction crossing region 14, preferably the integrated
elastic lead-lag hinge 4 of the elastic torsion element 5d is formed. Preferentially,
the integrated elastic lead-lag hinge 4 is formed by a narrowest cross-section area
of the elastic torsion element 5d. By way of example, this narrowest cross-section
is formed by the predetermined fiber direction region 14.
[0052] It should be noted that the elastic torsion element 5d is only illustrated partly
in Figure 2 for clarity and simplicity of the representation, in order to illustrate
a preferred configuration of the integrated elastic lead-lag hinge 4. The integrated
elastic lead-lag hinge 4 is illustratively arranged in an associated elastic lead-lag
hinge area 13a of the elastic torsion element 5d. However, the latter preferably also
comprises an optional elastic flapping hinge area 13b and a rotor blade attachment
area 13c, i. e. a transition zone 13c to a respective aerodynamic profile.
[0053] Figure 3 shows the elastic torsion element 5d of Figure 2 with the longitudinal axis
5f and the elastically deformable plate 11a. Again, the elastic torsion element 5d
is only partly illustrated by means of the elastic lead-lag hinge area 13a, where
the integrated elastic lead-lag hinge 4 of Figure 2 is located. However, the elastic
flapping hinge area 13b and the rotor blade attachment area or transition zone to
an associated aerodynamic profile 13c are, similar to Figure 2, not illustrated in
greater detail.
[0054] In contrast to Figure 2, the elastic torsion element 5d is now shown as full laminate
21 including the dominant uninterrupted fibers as described above with reference to
Figure 2, as well as interrupted fibers and spliced plies. These interrupted fibers
and spliced plies preferably round off sharp corners, create smooth transitions, increase
a respective in-plane shear strength, and avoid excessively low thicknesses of the
elastic torsion element 5d. Accordingly, in contrast to the partial laminate 20 of
Figure 2, the full laminate 21 of Figure 3 is illustrated with respectively rounded
edges.
[0055] By way of example, the elastic torsion element 5d and, illustratively, the elastically
deformable plate 11a now comprises an opening 11i. However, this opening 11i is optional
and not mandatory, so that this opening 11i can likewise be omitted.
[0056] Figure 4 shows the elastic torsion element 5d with the longitudinal axis 5f of Figure
3 for further illustrating the multiplicity of elastically deformable plates 11 of
Figure 3. As described above with reference to Figure 2, the multiplicity of elastically
deformable plates 11 preferably comprises at least two and, preferentially, four elastically
deformable plates 11a, 11b, 11c, 11d.
[0057] According to one aspect, the elastically deformable plate 11a and, preferably, each
one of the elastically deformable plates 11a, 11b, 11c, 11d exhibits at least approximately
an arc-shaped, i. e. curved cross-section. Preferably, each one of the elastically
deformable plates 11a, 11b, 11c, 11d, exhibits this at least approximately arc-shaped
cross-section at least in an associated elastic lead-lag hinge area (13a in Figure
2 and Figure 3) of the integrated elastic lead-lag hinge 4, as illustrated in Figure
4. In other words, each one of the elastically deformable plates 11a, 11b, 11c, 11d
is at least partly U-shaped.
[0058] In Figure 4, the elastically deformable plates 11a, 11b form illustratively upper
deformable plates, while the elastically deformable plates 11c, 11d illustratively
form lower deformable plates, both with respect to the longitudinal axis 5f of the
elastic torsion element 5d. According to one aspect, the lower elastically deformable
plates 11c, 11d are arranged in reflection symmetry to the upper elastically deformable
plates 11a, 11b.
[0059] Figure 5 shows the elastically deformable plates 11a, 11b, 11c, 11d of the multiplicity
of elastically deformable plates 11 of Figure 4 of the integrated elastic lead-lag
hinge 4 of Figure 3. However, the elastically deformable plates 11a, 11b, 11c, 11d
are in contrast to Figure 4 now illustrated in a location that is closer to the elastic
flapping hinge area 13b of Figure 3.
[0060] As can be seen from Figure 5, each one of the elastically deformable plates 11a,
11b, 11c, and 11d is less curved than in Figure 4. Furthermore, each one of the elastically
deformable plates 11a, 11b, 11c, 11d now comprises a dominant fiber direction overlapping
area 15a, where the dominant fiber directions 12a, 12b of Figure 2 overlap each other,
as well as single dominant fiber direction areas 15b, 15c. In other words, when looking
at Figure 5 in combination with Figure 2, it becomes clear that the unidirectional
fibers coming from the single dominant fiber direction areas 15b, 15c cross each other
in the dominant fiber directions overlapping area 15a, thereby thickening this overlapping
area 15a compared to the single dominant fiber direction areas 15b, 15c.
[0061] According to one aspect, the arc-shaped cross-section of the elastically deformable
plates 11a, 11b, 11c, 11d is flattened with respect to Figure 4, as described above.
According to one aspect, this flattening continues in direction of the elastic flapping
hinge area 13b of Figure 3. Thus, the integrated elastic lead-lag hinge 4 preferably
transitions along the longitudinal axis 5f of the elastic torsion element 5d from
the elastic lead-lag hinge area 13a of Figure 3 towards the elastic flapping hinge
area 13b of Figure 3 from the arc-shaped cross-section into a flat cross-section.
Likewise, the arc-shaped cross-section of the elastically deformable plates 11a, 11b,
11c, 11d in the elastic lead-lag hinge area 13a of Figure 3 of the integrated elastic
lead-lag hinge 4 preferably transitions along the longitudinal axis 5f of the elastic
torsion element 5d towards the rotor blade attachment area or transition zone 13c
of Figure 3 into a flat cross-section. It should be noted that this is exemplarily
further illustrated in Figure 11.
[0062] Figure 6 shows the elastic torsion element 5d of Figure 2, i. e. the partial laminate
20 of uninterrupted fibers that follow the dominant fiber directions 12a, 12b of Figure
2. However, in contrast to Figure 2, selected fibers of the fiber reinforced polymers
that form the elastically deformable plate 11a are according to one aspect now arranged
along at least one third dominant fiber direction 12c. This at least one third dominant
fiber direction 12c preferably crosses the other two dominant fiber directions 12e,
12b, preferentially in the fiber direction crossing region 14 of Figure 2.
[0063] Figure 7 shows the elastic torsion element 5d according to Figure 6. However, in
contrast to Figure 6 and in analogy to Figure 3, the elastic torsion element 5d is
now illustrated as full laminate 21 with the dominant uninterrupted fibers that are
arranged along the three dominant fiber directions 12a, 12b, 12c of Figure 6. The
full laminate 21 also comprises interrupted fibers and spliced plies, which round
off respective sharp corners, create smooth transitions, increase a respective in-plane
shear strength of the elastic torsion element 5d, and avoid excessively low thicknesses
thereof.
[0064] Figure 8 shows the multiplicity of elastically deformable plates 11 of Figure 6 and
Figure 7, or of Figure 2 and Figure 3, according to a variant with only three elastically
deformable plates, i. e. the elastically deformable plates 11a, 11d of Figure 4, and
an additional elastically deformable plate 11e. The elastically deformable plates
11a, 11d are illustratively embodied according to Figure 4 and arranged in reflection
symmetry. The elastically deformable plate 11e is according to one aspect arranged
between the elastically deformable plates 11a, 11d.
[0065] Preferably, the elastically deformable plate 11e exhibits a point symmetric cross-section,
preferentially at least in the elastic lead-lag hinge area 13a of Figure 2, Figure
3, Figure 6 and Figure 7. More specifically, the elastically deformable plate 11e
exemplarily defines a rectangular cross-section.
[0066] Figure 9 shows the elastic torsion element 5d of Figure 8 with the elastically deformable
plates 11a, 11d. However, in contrast to Figure 8 the elastically deformable plate
11e of Figure 8 with the rectangular cross-section is now exemplarily replaced by
an elastically deformable plate 11f, which is still point symmetric, but illustratively
exhibits at least approximately an S-shaped cross-section in the elastic lead-lag
hinge area 13a of Figure 2, Figure 3, Figure 6 and Figure 7.
[0067] Figure 10 shows the elastic torsion element 5d of Figure 4 with the multiplicity
of elastically deformable plates 11 that comprises the elastically deformable plates
11a, 11b, 11c, 11d of Figure 4. However, in contrast to Figure 4, the elastically
deformable plates 11a, 11b, 11c, 11d are now rigidly mounted to each other by means
of a bolted connection 16. According to one aspect, the bolted connection 16 is formed
by means of an exemplary connection bolt 16a at least in close proximity and, preferably,
in the region of the longitudinal axis 5f of the elastic torsion element 5d.
[0068] Figure 11 shows the elastic torsion element 5d of Figure 2 to Figure 5 with its longitudinal
axis 5f and with the multiplicity of elastically deformable plates 11 that comprises
according to Figure 4 and Figure 5 the elastically deformable plates 11a, 11b, 11c,
11d. The elastic torsion element 5d is again only partly shown and illustrated with
a direction 18a that exemplarily points towards the rotor blade attachment area or
transition zone 13c of Figure 2 and Figure 3, as well as a direction 18b that points
towards the elastic flapping hinge area 13b of Figure 2 and Figure 3.
[0069] However, in contrast to Figure 4 and Figure 5, the elastically deformable plates
11a, 11b are now preferably integrated into a single slotted elastically deformable
plate 11g. More specifically, according to one aspect the elastically deformable plates
11a, 11b are at least partly separated in the single slotted elastically deformable
plate 11g by means of an associated separating gap or slot 17a. This associated separating
gap or slot 17a is preferably at least provided in the elastic lead-lag hinge area
13a of the elastic torsion element 5d, i. e. at the integrated elastic lead-lag hinge
4 thereof. Illustratively, the associated separating gap or slot 17a is only provided
in a central portion of the elastic lead-lag hinge area 13a, i. e. preferably not
in transition regions towards the rotor blade attachment area or transition zone 13c
of Figure 2 and Figure 3, as well as towards the elastic flapping hinge area 13b of
Figure 2 and Figure 3.
[0070] Likewise, the elastically deformable plates 11c, 11d are preferably integrated into
a single slotted elastically deformable plate 11h. More specifically, according to
one aspect the elastically deformable plates 11c, 11d are at least partly separated
in the single slotted elastically deformable plate 11h by means of an associated separating
gap or slot 17b. This associated separating gap or slot 17b is preferably also at
least provided in the elastic lead-lag hinge area 13a of the elastic torsion element
5d, i. e. at the integrated elastic lead-lag hinge 4 thereof. Illustratively, the
associated separating gap or slot 17b is only provided in a central portion of the
elastic lead-lag hinge area 13a, i. e. preferably not in transition regions towards
the rotor blade attachment area or transition zone 13c of Figure 2 and Figure 3, as
well as towards the elastic flapping hinge area 13b of Figure 2 and Figure 3.
[0071] For further illustrating the separating gaps or slots 17a, 17b, a cut view of the
central section of the elastic lead-lag hinge area 13a is shown in enlarged form in
a detail view 19a. Moreover, for further illustrating the slotted elastically deformable
plates 11g, 11h outside of this central section, i. e. by way of example in the transition
region towards the elastic flapping hinge area 13b of Figure 2 and Figure 3, a further
enlarged cut view 19b is also shown.
[0072] It should be noted that the above described embodiments are merely described to illustrate
possible realizations of the present invention, but not in order to restrict the present
invention thereto.
[0073] By way of example, the two upper elastically deformable plates 11a, 11b of Figure
4 may be replaced with the single slotted elastically deformable plate 11g of Figure
11. Likewise, the two lower elastically deformable plates 11c, 11d of Figure 4 may
be replaced with the single slotted elastically deformable plate 11h of Figure 11.
Moreover, the slotted elastically deformable plates 11g, 11h of Figure 11 may be attached
to each other by means of the bolted connection 16 according to Figure 10. Furthermore,
the flat elastically deformable plate 11e of Figure 8 can be introduced between the
slotted elastically deformable plates 11g, 11h of Figure 11. This similarly applies
to the S-shaped elastically deformable plate 11f of Figure 9, that may likewise be
introduced between the slotted elastically deformable plates 11g, 11h of Figure 11.
Moreover, also the configurations of Figure 8 and Figure 9 may be provided with the
bolted connection 16 of Figure 10, and so on.
Reference List
[0074]
1 multi-blade rotor
2a, 2b, 2c, 2d, 2e rotor blades
3 elastic hinge unit
3a, 3b, 3c, 3d, 3e blade connecting points
4 integrated elastic lead-lag hinge
5 multiplicity of elastic torsion elements
5a, 5b, 5c, 5d, 5e elastic torsion elements
5f elastic torsion element longitudinal axis
6 multiplicity of control cuffs
6a, 6b, 6c, 6d, 6e control cuffs
7 rotor hub
8 rotor shaft
9 rotor head covering cap
9a rotor head covering cap cut-out
10 plurality of hub connecting points
10a hub connecting point
11 multiplicity of elastically deformable plates
11a, 11b, 11c, 11d partly U-shaped elastically deformable plates
11e flat elastically deformable plate
11f S-shaped elastically deformable plate
11g, 11h slotted elastically deformable plates
11i plate opening
12a, 12b, 12c dominant fiber directions
13a elastic lead-lag hinge area
13b elastic flapping hinge area
13c rotor blade attachment area or transition zone
14 fiber direction crossing region
15a dominant fiber directions overlapping area
15b, 15c single dominant fiber direction area
16 bolted connection
16a connection bolt
17a, 17b separating gaps or slots
18a direction towards rotor blade attachment area or transition zone
18b direction towards elastic flapping hinge area
19a cut view of central section at elastic lead-lag hinge area
19b cut view of intermediate section between elastic lead-lag hinge area and rotor
blade attachment area or transition zone
20 partial laminate of uninterrupted fibers following dominant fiber directions
21 full laminate including dominant uninterrupted fibers, interrupted fibers and spliced
plies
1. An elastic torsion element (5d) for connecting a rotor blade (2d) to a rotor hub (7)
of a rotor (1), the elastic torsion element (5d) comprising at least two elastically
deformable plates (11a, 11b, 11c, 11d), wherein each one of the at least two elastically
deformable plates (11a, 11b, 11c, 11d) comprises fiber reinforced polymers, wherein
respective fibers of the fiber reinforced polymers of each one of the at least two
elastically deformable plates (11a, 11b, 11c, 11d) are at least arranged along a first
and a second dominant fiber directions (12a, 12b), and wherein the elastic torsion
element (5d) comprises an integrated elastic lead-lag hinge (4) characterized in that the first dominant fiber direction (12a) crosses the second dominant fiber direction
(12b) in a predetermined fiber direction crossing region (14), and the lead-lag hinge
(4) is formed at the predetermined fiber direction crossing region (14).
2. The elastic torsion element (5d) of claim 1,
wherein the fiber reinforced polymers comprise carbon, glass, aramid and/or basalt
fiber fabrics and rovings.
3. The elastic torsion element (5d) of claim 2,
wherein the respective fibers of the fiber reinforced polymers of each one of the
at least two elastically deformable plates (11a, 11b, 11c, 11d) are at least essentially
oriented within +/- 15° with respect to a longitudinal axis (5f) of the elastic torsion
element (5d).
4. The elastic torsion element (5d) of claim 1,
wherein respective fibers of the fiber reinforced polymers of each one of the at least
two elastically deformable plates (11a, 11b, 11c, 11d) are at least arranged along
one third dominant fiber direction (12c) that crosses at least one of the first dominant
fiber direction (12a) and the second dominant fiber direction (12b).
5. The elastic torsion element (5d) of claim 1,
wherein the at least two elastically deformable plates (11a, 11b, 11c, 11d) comprise
at least a first and a second elastically deformable plate (11a, 11b) that exhibit
at least approximately an arc-shaped cross-section in a respective elastic lead-lag
hinge area (13a) of the integrated elastic lead-lag hinge (4).
6. The elastic torsion element (5d) of claim 5,
wherein the at least two elastically deformable plates (11a, 11b, 11c, 11d) comprise
at least one third elastically deformable plate (11e) that is arranged between the
first and second elastically deformable plates (11a, 11b) and exhibits a point symmetric
cross-section in the respective elastic lead-lag hinge area (13a).
7. The elastic torsion element (5d) of claim 6,
wherein the at least one third elastically deformable plate (11e) exhibits a rectangular
cross-section in the respective elastic lead-lag hinge area (13a).
8. The elastic torsion element (5d) of claim 6,
wherein the at least one third elastically deformable plate (11e) exhibits at least
approximately an S-shaped cross-section in the respective elastic lead-lag hinge area
(13a).
9. The elastic torsion element (5d) of claim 5,
wherein the at least approximately arc-shaped cross-section in the respective elastic
lead-lag hinge area (13a) of the integrated elastic lead-lag hinge (4) transitions
along a longitudinal axis (5f) of the elastic torsion element (5d) towards an elastic
flapping hinge area (13b) into a flat cross-section.
10. The elastic torsion element (5d) of claim 5,
wherein the at least approximately arc-shaped cross section in the respective elastic
lead-lag hinge area (13a) of the integrated elastic lead-lag hinge (4) transitions
along a longitudinal axis (5f) of the elastic torsion element (5d) towards a rotor
blade attachment area or transition zone (13c) into a flat cross-section.
11. The elastic torsion element (5d) of claim 1,
wherein the integrated elastic lead-lag hinge (4) is formed by a narrowest cross-section
area of the elastic torsion element (5d).
12. The elastic torsion element (5d) of claim 1,
wherein the at least two elastically deformable plates (11a, 11b, 11c, 11d) comprise
at least two upper elastically deformable plates (11a, 11b) and at least two lower
elastically deformable plates (11c, 11d), and wherein the at least two lower elastically
deformable plates (11c, 11d) are arranged in reflection symmetry to the at least two
upper elastically deformable plates (11a, 11b).
13. The elastic torsion element (5d) of claim 12,
wherein the at least two lower elastically deformable plates (11c, 11d) are attached
to the at least two upper elastically deformable plates (11a, 11b) by means of a bolted
connection (16), the bolted connection (16) being provided at least approximately
at a longitudinal axis (5f) of the elastic torsion element (5d).
14. The elastic torsion element (5d) of claim 1,
wherein at least one first and one second elastically deformable plates (11a, 11b)
of the at least two elastically deformable plates (11a, 11b, 11c, 11d) are integrated
into a single slotted elastically deformable plate (11g), and wherein the at least
one first and one second elastically deformable plates (11a, 11b) are at least partly
separated in the single slotted elastically deformable plate (11g) by means of an
associated separating slot (17a).
15. A rotary wing aircraft with at least one rotor (1) that comprises at least two rotor
blades (2d, 2b), and with a rotor hub (7), each one of the at least two rotor blades
(2d, 2b) being connected to the rotor hub (7) via an elastic torsion element (5d)
according to one of the preceding claims.
1. Elastisches Torsionselement (5d) zum Verbinden eines Rotorblattes (2d) mit einer Rotornabe
(7) eines Rotors (1), wobei das elastische Torsionselement (5d) mindestens zwei elastisch
verformbare Platten (11a, 11b, 11c, 11d) umfasst, wobei jede der mindestens zwei elastisch
verformbaren Platten (11a, 11b, 11c, 11d) faserverstärkte Polymere umfasst, wobei
die jeweiligen Fasern der faserverstärkten Polymere jeder der mindestens zwei elastisch
verformbaren Platten (11a, 11b, 11c, 11d) mindestens entlang einer ersten und einer
zweiten vorherrschenden Faserrichtung (12a, 12b) angeordnet sind, und wobei das elastische
Torsionselement (5d) ein integriertes elastisches Lead-Lag-Gelenk (4) umfasst,
dadurch gekennzeichnet, dass die erste vorherrschende Faserrichtung (12a) die zweite vorherrschende Faserrichtung
(12b) in einem vorgegebenen Faserrichtungs-Kreuzungsbereich (14) kreuzt, und das Lead-Lag-Gelenk
(4) an dem vorgegebenen Faserrichtungs-Kreuzungsbereich (14) ausgebildet ist.
2. Elastisches Torsionselement (5d) nach Anspruch 1, bei dem die faserverstärkten Polymere
Kohlenstoff-, Glas-, Aramid- und/oder Basaltfasergewebe und -rovings umfassen.
3. Elastisches Torsionselement (5d) nach Anspruch 2, bei dem die jeweiligen Fasern der
faserverstärkten Polymere einer jeden der mindestens zwei elastisch verformbaren Platten
(11a, 11b, 11c, 11d) mindestens im Wesentlichen innerhalb von +/- 15° in Bezug auf
eine Längsachse (5f) des elastischen Torsionselements (5d) orientiert sind.
4. Elastisches Torsionselement (5d) nach Anspruch 1, bei dem die jeweiligen Fasern der
faserverstärkten Polymere einer jeden der mindestens zwei elastisch verformbaren Platten
(11a, 11b, 11c, 11d) mindestens entlang einer dritten vorherrschenden Faserrichtung
(12c) angeordnet sind, die die erste vorherrschende Faserrichtung (12a) und/oder die
zweite vorherrschende Faserrichtung (12b) kreuzt.
5. Elastisches Torsionselement (5d) nach Anspruch 1, bei dem die mindestens zwei elastisch
verformbaren Platten (11a, 11b, 11c, 11d) mindestens eine erste und eine zweite elastisch
verformbare Platte (11a, 11b) umfassen, die in einem jeweiligen elastischen Lead-Lag-Gelenkbereich
(13a) des integrierten elastischen Lead-Lag-Gelenks (4) mindestens annähernd einen
bogenförmigen Querschnitt aufweisen.
6. Elastisches Torsionselement (5d) nach Anspruch 5, bei dem die mindestens zwei elastisch
verformbaren Platten (11a, 11b, 11c, 11d) mindestens eine dritte elastisch verformbare
Platte (11e) umfassen, die zwischen der ersten und zweiten elastisch verformbaren
Platte (11a, 11b) angeordnet ist und in dem jeweiligen elastischen Lead-Lag-Gelenkbereich
(13a) einen punktsymmetrischen Querschnitt aufweist.
7. Elastisches Torsionselement (5d) nach Anspruch 6, bei dem die mindestens eine dritte
elastisch verformbare Platte (11e) in dem jeweiligen elastischen Lead-Lag-Gelenkbereich
(13a) einen rechteckigen Querschnitt aufweist.
8. Elastisches Torsionselement (5d) nach Anspruch 6, bei dem die mindestens eine dritte
elastisch verformbare Platte (11e) in dem jeweiligen elastischen Lead-Lag-Gelenkbereich
(13a) mindestens annähernd einen S-förmigen Querschnitt aufweist.
9. Elastisches Torsionselement (5d) nach Anspruch 5, bei dem der mindestens annähernd
bogenförmige Querschnitt in dem jeweiligen elastischen Lead-Lag-Gelenkbereich (13a)
des integrierten elastischen Lead-Lag-Gelenks (4) entlang einer Längsachse (5f) des
elastischen Torsionselements (5d) zu einem elastischen Schlaggelenk (13b) hin in einen
flachen Querschnitt übergeht.
10. Elastisches Torsionselement (5d) nach Anspruch 5, bei dem der mindestens annähernd
bogenförmige Querschnitt im jeweiligen elastischen Lead-Lag-Gelenkbereich (13a) des
integrierten elastischen Lead-Lag-Gelenks (4) entlang einer Längsachse (5f) des elastischen
Torsionselements (5d) zu einem Rotorblattbefestigungsbereich oder einer Übergangszone
(130) hin in einen flachen Querschnitt übergeht.
11. Elastisches Torsionselement (5d) nach Anspruch 1, bei dem das integrierte elastische
Lead-Lag-Gelenk (4) durch eine engste Querschnittsfläche des elastischen Torsionselements
(5d) gebildet ist.
12. Elastisches Torsionselement (5d) nach Anspruch 1, bei dem die mindestens zwei elastisch
verformbaren Platten (11a, 11b, 11c, 11d) mindestens zwei obere elastisch verformbare
Platten (11a, 11b) und mindestens zwei untere elastisch verformbare Platten (11c,
11d) umfassen und bei dem die mindestens zwei unteren elastisch verformbaren Platten
(11c, 11d) spiegelsymmetrisch zu den mindestens zwei oberen elastisch verformbaren
Platten (11a, 11b) angeordnet sind.
13. Elastisches Torsionselement (5d) nach Anspruch 12, bei dem die mindestens zwei unteren
elastisch verformbaren Platten (11c, 11d) an den mindestens zwei oberen elastisch
verformbaren Platten (11a, 11b) mittels einer Schraubverbindung (16) befestigt sind,
wobei die Schraubverbindung (16) mindestens annähernd an einer Längsachse (5f) des
elastischen Torsionselements (5d) vorgesehen ist.
14. Elastisches Torsionselement (5d) nach Anspruch 1, bei dem mindestens eine erste und
eine zweite elastisch verformbare Platte (11a, 11b) der mindestens zwei elastisch
verformbaren Platten (11a, 11b, 11c, 11d) in eine einzelne geschlitzte elastisch verformbare
Platte (11g) integriert sind, und bei dem die mindestens eine erste und eine zweite
elastisch verformbare Platte (11a, 11b) in der einzelnen geschlitzten elastisch verformbaren
Platte (11g) mittels eines zugeordneten Trennschlitzes (17a) zumindest teilweise getrennt
sind.
15. Drehflügelflugzeug mit mindestens einem Rotor (1), der mindestens zwei Rotorblätter
(2d, 2b) umfasst, und mit einer Rotornabe (7), wobei jedes der mindestens zwei Rotorblätter
(2d, 2b) über ein elastisches Torsionselement (5d) nach einem der vorstehenden Ansprüche
mit der Rotornabe (7) verbunden ist.
1. Élément de torsion élastique (5d) pour raccorder une pale de rotor (2d) à un moyeu
de rotor (7) d'un rotor (1), l'élément de torsion élastique (5d) comprend au moins
deux plaques élastiquement déformables (11a, 11b, 11c, 11d), dans lequel chacune des
au moins deux plaques élastiquement déformables (11a, 11b, 11c, 11d) comprend des
polymères renforcés de fibres, dans lequel les fibres respectives des polymères renforcés
de fibres de chacune des au moins deux plaques élastiquement déformables (11a, 11b,
11c, 11d) sont au moins agencées suivant une parmi une première et une deuxième directions
dominantes de fibre (12a, 12b) et dans lequel l'élément de torsion élastique (5d)
comprend une articulation de traînée élastique intégrée (4),
caractérisé en ce que la première direction dominante de fibre (12a) croise la deuxième direction dominante
de fibre (12b) dans une zone de croisement de direction de fibres prédéterminée (14),
et l'articulation de traînée (4) est formée dans la zone de croisement de direction
de fibre prédéterminée (14).
2. Élément de torsion élastique (5d) selon la revendication 1, dans lequel les polymères
renforcés de fibres comprennent des toiles et des stratifils de fibres de carbone,
de verre, d'aramide et/ou de basalte.
3. Élément de torsion élastique (5d) selon la revendication 2, dans lequel les fibres
respectives des polymères renforcés de fibres de chacune des au moins deux plaques
élastiquement déformables (11a, 11b, 11c, 11d) sont au moins essentiellement orientées
suivant un angle de +/- 15 degrés par rapport à un axe longitudinal (5f) de l'élément
de torsion élastique (5d).
4. Élément de torsion élastique (5d) selon la revendication 1, dans lequel les fibres
respectives des polymères renforcés de fibres de chacune des au moins deux plaques
élastiquement déformables (11a, 11b, 11c, 11d) sont au moins agencées le long d'une
troisième direction dominante de fibre (12c) qui croise au moins une parmi la première
direction dominante de fibre (12a) et la deuxième direction dominante de fibre (12b).
5. Élément de torsion élastique (5d) selon la revendication 1, dans lequel les au moins
deux plaques élastiquement déformables (11a, 11b, 11c, 11d) comprennent au moins une
première et une deuxième plaque élastiquement déformable (11a, 11b) qui présentent
au moins approximativement une section transversale en forme d'arc dans une zone d'articulation
de traînée élastique respective (13a) de l'articulation de traînée élastique intégrée
(4).
6. Élément de torsion élastique (5d) selon la revendication 5, dans lequel les au moins
deux plaques élastiquement déformables (11a, 11b, 11c, 11d) comprennent au moins une
troisième plaque élastiquement déformable (11e) qui est agencée entre la première
et la deuxième plaque élastiquement déformable (11a, 11b) et présente une section
transversale en symétrie centrale dans la zone d'articulation de traînée élastique
respective (13a).
7. Élément de torsion élastique (5d) selon la revendication 6, dans lequel la au moins
une troisième plaque élastiquement déformable (11e) présente une section transversale
rectangulaire dans la zone d'articulation de trainée élastique respective (13a).
8. Élément de torsion élastique (5d) selon la revendication 6, dans lequel la au moins
une troisième plaque élastiquement déformable (11e) présente au moins approximativement
une section transversale en forme de S dans la zone d'articulation de trainée élastique
respective (13a).
9. Élément de torsion élastique (5d) selon la revendication 5, dans lequel la au moins
une section transversale approximativement en forme d'arc dans la zone d'articulation
de traînée élastique respective (13a) de l'articulation de traînée élastique intégrée
(4) effectue une transition le long de l'axe longitudinal (5f) de l'élément de torsion
élastique (5d) vers une zone d'articulation de battement élastique (13b) de section
transversale plate.
10. Élément de torsion élastique (5d) selon la revendication 5, dans lequel la au moins
une section transversale au moins approximativement en forme d'arc dans la zone d'articulation
de traînée élastique respective (13a) de l'articulation de traînée élastique intégrée
(4) effectue une transition le long de l'axe longitudinal (5f) de l'élément de torsion
élastique (5d) vers une zone de fixation de la pale de rotor ou une zone de transition
(13c) de section transversale plate.
11. Élément de torsion élastique (5d) selon la revendication 1, dans lequel l'articulation
de traînée élastique intégrée (4) est formée par la zone de section transversale la
plus étroite de l'élément de torsion élastique (5d).
12. Élément de torsion élastique (5d) selon la revendication 1, dans lequel les au moins
deux plaques élastiquement déformables (11a, 11b, 11c, 11d) comprennent au moins deux
plaques élastiquement déformables supérieures (11a, 11b) et au moins deux plaques
élastiquement déformables inférieures (11c, 11d), et dans lequel les au moins deux
plaques élastiquement déformables inférieures (11c, 11d) sont agencées en symétrie
axiale par rapport aux au moins deux plaques élastiquement déformables supérieures
(11a, 11b).
13. Élément de torsion élastique (5d) selon la revendication 12, dans lequel les au moins
deux plaques élastiquement déformables inférieures (11c, 11d) sont fixées aux au moins
deux plaques élastiquement déformables supérieures (11a, 11b) au moyen d'un raccordement
boulonné (16), le raccordement boulonné (16) étant prévu au moins approximativement
sur un axe longitudinal (5f) de l'élément de torsion élastique (5d).
14. Élément de torsion élastique (5d) selon la revendication 1, dans lequel au moins une
première et une deuxième plaque élastiquement déformables (11a, 11b) des au moins
deux plaques élastiquement déformables (11a, 11b, 11c, 11d) sont intégrées dans une
unique plaque élastiquement déformable à fente (11g), et dans lequel les au moins
une première et deuxième plaque élastiquement déformable (11a, 11b) sont au moins
en partie séparées dans l'unique plaque élastiquement déformable à fente (11g) au
moyen d'une fente de séparation associée (17a).
15. Aéronef à voilure tournante avec au moins un rotor (1) comprenant au moins deux pales
de rotor (2d, 2b), avec un moyeu de rotor (7), chacune des au moins deux pales de
rotor (2d, 2b) étant raccordée au moyeu de rotor (7) par un élément de torsion élastique
(5d) selon l'une quelconque des revendications précédentes.